Summertime was a particularly difficult season to get through; the store never seemed to be comfortable. The chilled water system didn’t produce its full load anymore, and the landlord didn’t always provide the proper amount of water at the proper temperature in order to keep the retail space cool.
Everything came to a head in the summer of 1999. The store became so unbearable that portable cooling units had to be brought in on tractor trailers. Engineers were subsequently hired to determine the best way to renovate or replace the hvac system.
Toys R Us managers didn’t like any of the suggestions, so they brought in a local contractor to help out. He suggested abandoning the chilled water system entirely and using high-efficiency rooftop units to heat and cool the space.
His idea made sense to all involved.
A decision is made
Steve Waxman, director of facilities, Toys R Us, was especially excited about the new system. Engineers had first informed him that the store required 110 tons of cooling, about 20 tons more than the existing chilled water system could handle, even when it was brand new.Then the engineers presented Waxman with three different options:
1. Put in new water-cooled packaged units with new cooling towers, with an outside source of chilled water;
2. Install an air-cooled, direct-expansion split system; or
3. Use an air-cooled split system in conjunction with some new, self-contained rooftop units.
None of these suggestions thrilled Waxman. So when a local contractor suggested rooftop units, Waxman thought it made sense.
“I wanted to increase comfort, and I didn’t want to keep using the landlord-supplied chilled water,” he says. In addition, Waxman wanted to add an energy management system and economizer capability, and he wanted a system that could be serviced easily. The rooftop units seemed a perfect fit.
The final system consists of two 25-ton and two 30-ton Lennox rooftop units, as well as a Novar energy management system to control them. The factory-installed economizers will supply fresh air to the store, which has not had any up until this point.
The rooftop units are the highest-efficiency, highest-quality units that Waxman says he could find. And he says that he regularly “kicks the tires” of all the different kinds of units out there. He doesn’t mind paying a premium for a quality product and neither do his superiors, because the overall lifecycle cost is much lower.
“A few years ago, we sat down and went through a return-on-investment analysis. We showed how spending a little more money up front is going to give returns down the road through lower energy costs and higher operating efficiency.”
In addition, Waxman says they’ll have lower maintenance costs because “From my perspective, the rooftop units are a much easier unit to maintain. We use them in most Toys R Us stores in the chain. We know how to maintain them, and we maintain them at a very efficient price.
“When you start getting into water, it’s a little more technical, and in my view, it’s also a little more complicated than what I want to take on. The packaged units are good 12 months out of the year, and the economizer can be used for in-between seasons.
“For a simple retail store application, I think it’s the best way to go.”
Tough installation
While the decision to use rooftop units may have been an easy one to make, deciding how to get them on the roof was another story.Being a multilevel store, it was not possible to move a crane close enough to the front of the store to set the units. Therefore, a 150-ton crane was brought in to swing the units approximately 150 ft across two parking lots.
Once the units were on the roof, they were placed on top of two existing penthouses, with a 25-ton and a 30-ton unit on each of the penthouses. “We had a lot of coordination with the landlord in order to make these penthouses structurally sound so they could support the units,” says Waxman.
Holes were cut in the roofs of the penthouses directly above the existing chillers, which were abandoned in place, and the rooftop units were placed over these openings. The supply and return ducts were taken down through the penthouses and then tied into the existing ductwork down below.
Waxman notes that while the installation went relatively smoothly and start-up was a breeze, the whole process took a little longer than he would have liked.
“It was a complex project, and we had to maintain the store operating while I was converting the new units up there. They couldn’t shut down the store for a couple of days, so we were only able to do one unit at a time.”
With the installation just completed in May, energy costs cannot yet be compared to the old system. However, Waxman believes he’ll save quite a bit of energy with the new system.
Beyond that, the store is the most comfortable it’s been in years. “The comfort level is great, and the store manager thinks the facilities department is the best department at Toys R Us.”
